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Chou SM, Yen YH, Yuan F, Zhang SC, Chong CM. Neuronal Senescence in the Aged Brain. Aging Dis 2023; 14:1618-1632. [PMID: 37196117 PMCID: PMC10529744 DOI: 10.14336/ad.2023.0214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Accepted: 02/14/2023] [Indexed: 05/19/2023] Open
Abstract
Cellular senescence is a highly complicated cellular state that occurs throughout the lifespan of an organism. It has been well-defined in mitotic cells by various senescent features. Neurons are long-lived post-mitotic cells with special structures and functions. With age, neurons display morphological and functional changes, accompanying alterations in proteostasis, redox balance, and Ca2+ dynamics; however, it is ambiguous whether these neuronal changes belong to the features of neuronal senescence. In this review, we strive to identify and classify changes that are relatively specific to neurons in the aging brain and define them as features of neuronal senescence through comparisons with common senescent features. We also associate them with the functional decline of multiple cellular homeostasis systems, proposing the possibility that these systems are the main drivers of neuronal senescence. We hope this summary will serve as a steppingstone for further inputs on a comprehensive but relatively specific list of phenotypes for neuronal senescence and in particular their underlying molecular events during aging. This will in turn shine light on the association between neuronal senescence and neurodegeneration and lead to the development of strategies to perturb the processes.
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Affiliation(s)
- Shu-Min Chou
- Program in Neuroscience & Behavioral Disorders, Duke-NUS Medical School, 169857 Singapore, Singapore.
| | - Yu-Hsin Yen
- Program in Neuroscience & Behavioral Disorders, Duke-NUS Medical School, 169857 Singapore, Singapore.
| | - Fang Yuan
- Program in Neuroscience & Behavioral Disorders, Duke-NUS Medical School, 169857 Singapore, Singapore.
| | - Su-Chun Zhang
- Program in Neuroscience & Behavioral Disorders, Duke-NUS Medical School, 169857 Singapore, Singapore.
- Department of Neuroscience, Department of Neurology, Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA.
| | - Cheong-Meng Chong
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macao, China.
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Case SL, Lin R, Thibault O. Age- and sex-dependent alterations in primary somatosensory cortex neuronal calcium network dynamics during locomotion. Aging Cell 2023; 22:e13898. [PMID: 37269157 PMCID: PMC10410056 DOI: 10.1111/acel.13898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Revised: 05/12/2023] [Accepted: 05/22/2023] [Indexed: 06/04/2023] Open
Abstract
Over the past 30 years, the calcium (Ca2+ ) hypothesis of brain aging has provided clear evidence that hippocampal neuronal Ca2+ dysregulation is a key biomarker of aging. Age-dependent Ca2+ -mediated changes in intrinsic excitability, synaptic plasticity, and activity have helped identify some of the mechanisms engaged in memory and cognitive decline based on work done mostly at the single-cell level and in the slice preparation. Recently, our lab identified age- and Ca2+ -related neuronal network dysregulation in the cortex of the anesthetized animal. Still, investigations in the awake animal are needed to test the generalizability of the Ca2+ hypothesis of brain aging. Here, we used in vigilo two-photon imaging in ambulating mice, to image GCaMP8f in the primary somatosensory cortex (S1), during ambulation and at rest. We investigated aging- and sex-related changes in neuronal networks in the C56BL/6J mouse. Following imaging, gait behavior was characterized to test for changes in locomotor stability. During ambulation, in both young adult and aged mice, an increase in network connectivity and synchronicity was noted. An age-dependent increase in synchronicity was seen in ambulating aged males only. Additionally, females displayed increases in the number of active neurons, Ca2+ transients, and neuronal activity compared to males, particularly during ambulation. These results suggest S1 Ca2+ dynamics and network synchronicity are likely contributors of locomotor stability. We believe this work raises awareness of age- and sex-dependent alterations in S1 neuronal networks, perhaps underlying the increase in falls with age.
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Affiliation(s)
- Sami L. Case
- Department of Pharmacology & Nutritional SciencesUniversity of Kentucky College of MedicineLexingtonKentuckyUSA
| | - Ruei‐Lung Lin
- Department of Pharmacology & Nutritional SciencesUniversity of Kentucky College of MedicineLexingtonKentuckyUSA
| | - Olivier Thibault
- Department of Pharmacology & Nutritional SciencesUniversity of Kentucky College of MedicineLexingtonKentuckyUSA
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3
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Takla M, Saadeh K, Tse G, Huang CLH, Jeevaratnam K. Ageing and the Autonomic Nervous System. Subcell Biochem 2023; 103:201-252. [PMID: 37120470 DOI: 10.1007/978-3-031-26576-1_10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/01/2023]
Abstract
The vertebrate nervous system is divided into central (CNS) and peripheral (PNS) components. In turn, the PNS is divided into the autonomic (ANS) and enteric (ENS) nervous systems. Ageing implicates time-related changes to anatomy and physiology in reducing organismal fitness. In the case of the CNS, there exists substantial experimental evidence of the effects of age on individual neuronal and glial function. Although many such changes have yet to be experimentally observed in the PNS, there is considerable evidence of the role of ageing in the decline of ANS function over time. As such, this chapter will argue that the ANS constitutes a paradigm for the physiological consequences of ageing, as well as for their clinical implications.
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Affiliation(s)
| | | | - Gary Tse
- Kent and Medway Medical School, Canterbury, UK
- University of Surrey, Guildford, UK
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4
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Zhu F, Miao Y, Cheng M, Ye X, Chen A, Zheng G, Tian X. The CACNA1A Mutant Disrupts Lysosome Calcium Homeostasis in Cerebellar Neurons and the Resulting Endo-Lysosomal Fusion Defect Can be Improved by Calcium Modulation. Neurochem Res 2021; 47:249-263. [PMID: 34476720 DOI: 10.1007/s11064-021-03438-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 08/23/2021] [Accepted: 08/25/2021] [Indexed: 11/24/2022]
Abstract
Mutations in P/Q type voltage gated calcium channel (VGCC) lead severe human neurological diseases such as episodic ataxia 2, familial hemiplegic migraine 1, absence epilepsy, progressive ataxia and spinocerebellar ataxia 6. The pathogenesis of these diseases remains unclear. Mice with spontaneous mutation in the Cacna1a gene encoding the pore-forming subunit of P/Q type VGCC also exhibit ataxia, epilepsy and neurodegeneration. Based on the previous work showing that the P/Q type VGCC in neurons regulates lysosomal fusion through its calcium channel activity on lysosomes, we utilized CACNA1A mutant mice to further investigate the mechanism by which P/Q-type VGCCs regulate lysosomal function and neuronal homeostasis. We found CACNA1A mutant neurons have reduced lysosomal calcium storage without changing the resting calcium concentration in cytoplasm and the acidification of lysosomes. Immunohistochemistry and transmission electron microscopy reveal axonal degeneration due to lysosome dysfunction in the CACNA1A mutant cerebella. The calcium modulating drug thapsigargin, by depleting the ER calcium store, which locally increases the calcium concentration can alleviate the defective lysosomal fusion in mutant neurons. We propose a model that in cerebellar neurons, P/Q-type VGCC maintains the integrity of the nervous system by regulating lysosomal calcium homeostasis to affect lysosomal fusion, which in turn regulates multiple important cellular processes such as autophagy and endocytosis. This study helps us to better understand the pathogenesis of P/Q-type VGCC related neurodegenerative diseases and provides a feasible direction for future pharmacological treatment.
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Affiliation(s)
- Feng Zhu
- Key Laboratory of Neuropsychiatric Drug Research of Zhejiang Province, Institute of Materia Medica, Hangzhou Medical College (Zhejiang Academy of Medical Sciences), Hangzhou, 310013, China.,Department of Pharmacy, Hangzhou Medical College, Hangzhou, 310013, China
| | - Yunping Miao
- Key Laboratory of Neuropsychiatric Drug Research of Zhejiang Province, Institute of Materia Medica, Hangzhou Medical College (Zhejiang Academy of Medical Sciences), Hangzhou, 310013, China.,Department of Pharmacy, Hangzhou Medical College, Hangzhou, 310013, China
| | - Min Cheng
- Key Laboratory of Neuropsychiatric Drug Research of Zhejiang Province, Institute of Materia Medica, Hangzhou Medical College (Zhejiang Academy of Medical Sciences), Hangzhou, 310013, China.,Department of Pharmacy, Hangzhou Medical College, Hangzhou, 310013, China
| | - Xiaodi Ye
- Key Laboratory of Neuropsychiatric Drug Research of Zhejiang Province, Institute of Materia Medica, Hangzhou Medical College (Zhejiang Academy of Medical Sciences), Hangzhou, 310013, China.,Department of Pharmacy, Hangzhou Medical College, Hangzhou, 310013, China
| | - Aiying Chen
- Key Laboratory of Neuropsychiatric Drug Research of Zhejiang Province, Institute of Materia Medica, Hangzhou Medical College (Zhejiang Academy of Medical Sciences), Hangzhou, 310013, China.,Department of Pharmacy, Hangzhou Medical College, Hangzhou, 310013, China
| | - Gaoli Zheng
- National Zhejiang Center for Safety Evaluation of New Drugs, Hangzhou Medical College (Zhejiang Academy of Medical Sciences), Hangzhou, 310013, China
| | - Xuejun Tian
- Key Laboratory of Neuropsychiatric Drug Research of Zhejiang Province, Institute of Materia Medica, Hangzhou Medical College (Zhejiang Academy of Medical Sciences), Hangzhou, 310013, China. .,Department of Pharmacy, Hangzhou Medical College, Hangzhou, 310013, China. .,Life Sciences Institute and Innovation Center for Cell Biology, Zhejiang University, Hangzhou, 310058, China.
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5
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Ghoweri AO, Ouillette L, Frazier HN, Anderson KL, Lin RL, Gant JC, Parent R, Moore S, Murphy GG, Thibault O. Electrophysiological and Imaging Calcium Biomarkers of Aging in Male and Female 5×FAD Mice. J Alzheimers Dis 2020; 78:1419-1438. [PMID: 33164928 PMCID: PMC7836067 DOI: 10.3233/jad-200109] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
BACKGROUND In animal models and tissue preparations, calcium dyshomeostasis is a biomarker of aging and Alzheimer's disease that is associated with synaptic dysfunction, neuritic pruning, and dysregulated cellular processes. It is unclear, however, whether the onset of calcium dysregulation precedes, is concurrent with, or is the product of pathological cellular events (e.g., oxidation, amyloid-β production, and neuroinflammation). Further, neuronal calcium dysregulation is not always present in animal models of amyloidogenesis, questioning its reliability as a disease biomarker. OBJECTIVE Here, we directly tested for the presence of calcium dysregulation in dorsal hippocampal neurons in male and female 5×FAD mice on a C57BL/6 genetic background using sharp electrodes coupled with Oregon-green Bapta-1 imaging. We focused on three ages that coincide with the course of amyloid deposition: 1.5, 4, and 10 months old. METHODS Outcome variables included measures of the afterhyperpolarization, short-term synaptic plasticity, and calcium kinetics during synaptic activation. Quantitative analyses of spatial learning and memory were also conducted using the Morris water maze. Main effects of sex, age, and genotype were identified on measures of electrophysiology and calcium imaging. RESULTS Measures of resting Oregon-green Bapta-1 fluorescence showed significant reductions in the 5×FAD group compared to controls. Deficits in spatial memory, along with increases in Aβ load, were detectable at older ages, allowing us to test for temporal associations with the onset of calcium dysregulation. CONCLUSION Our results provide evidence that reduced, rather than elevated, neuronal calcium is identified in this 5×FAD model and suggests that this surprising result may be a novel biomarker of AD.
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Affiliation(s)
- Adam O Ghoweri
- UKMC MS313, Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY, USA
| | - Lara Ouillette
- 5037 BSRB, Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, USA
| | - Hilaree N Frazier
- UKMC MS313, Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY, USA
| | - Katie L Anderson
- UKMC MS313, Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY, USA
| | - Ruei-Lung Lin
- UKMC MS313, Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY, USA
| | - John C Gant
- UKMC MS313, Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY, USA
| | - Rachel Parent
- 5037 BSRB, Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, USA
| | - Shannon Moore
- 5037 BSRB, Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, USA.,5037 BSRB, Molecular and Integrative Physiology, Michigan Neuroscience Institute, University of Michigan, Ann Arbor, MI, USA
| | - Geoffrey G Murphy
- 5037 BSRB, Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, USA.,5037 BSRB, Molecular and Integrative Physiology, Michigan Neuroscience Institute, University of Michigan, Ann Arbor, MI, USA
| | - Olivier Thibault
- UKMC MS313, Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY, USA
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6
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Teissier T, Boulanger E, Deramecourt V. Normal ageing of the brain: Histological and biological aspects. Rev Neurol (Paris) 2020; 176:649-660. [PMID: 32418702 DOI: 10.1016/j.neurol.2020.03.017] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Revised: 03/20/2020] [Accepted: 03/23/2020] [Indexed: 02/02/2023]
Abstract
All the hallmarks of ageing are observed in the brain, and its cells, especially neurons, are characterized by their remarkably long lifetime. Like any organ or system, the brain is exposed to ageing processes which affect molecules, cells, blood vessels, gross morphology and, uniquely for this organ, cognition. The preponderant cerebral structures are characterized by the cellular processes of neurons and glial cells and while the quantity of cerebral interstitial fluid is limited, it is now recognized as playing a crucial role in maintaining cerebral homeostasis. Most of our current knowledge of the ageing brain derives from studies of neurodegenerative disorders. It is interesting to note that common features of these disorders, like Tau, phosphoTau and amyloid peptide accumulation, can begin relatively early in life as a result of physiological ageing and are present in subclinical cases while also being used as early-stage markers of neurodegenerative diseases in progression. In this article, we review tissue and cellular modifications in the ageing brain. Commonly described macroscopic, microscopic and vascular changes that in the ageing brain are contrasted with those seen in neurodegenerative contexts. We also review the molecular changes that occur with age in the brain, such as modifications in gene expression, insulin/insulin-like growth factor 1 signalling dysfunction, post-translational protein modifications, mitochondrial dysfunction, autophagy and calcium conductance changes.
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Affiliation(s)
- T Teissier
- Inserm, université de Lille, CHU de Lille, Institut Pasteur de Lille, U1167 - RID-AGE - facteurs de risque et déterminants moléculaires des maladies liées au vieillissement, équipe « de l'inflammation au vieillissement, 59000 Lille, France.
| | - E Boulanger
- Inserm, université de Lille, CHU de Lille, Institut Pasteur de Lille, U1167 - RID-AGE - facteurs de risque et déterminants moléculaires des maladies liées au vieillissement, équipe « de l'inflammation au vieillissement, 59000 Lille, France; Pôle de gérontologie, CHU de Lille, 59000 Lille, France
| | - V Deramecourt
- Inserm, UMR-S 1172 « Alzheimer et Tauopathies », centre mémoire de ressources et de recherche, Labex DISTALZ, université de Lille, CHU de Lille, 59000 Lille, France; Pôle de neurologie, CHU de Lille, 59000 Lille, France
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7
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Chandran R, Kumar M, Kesavan L, Jacob RS, Gunasekaran S, Lakshmi S, Sadasivan C, Omkumar R. Cellular calcium signaling in the aging brain. J Chem Neuroanat 2019; 95:95-114. [DOI: 10.1016/j.jchemneu.2017.11.008] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Revised: 09/03/2017] [Accepted: 11/07/2017] [Indexed: 12/21/2022]
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8
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Mirzakhalili E, Epureanu BI, Gourgou E. A mathematical and computational model of the calcium dynamics in Caenorhabditis elegans ASH sensory neuron. PLoS One 2018; 13:e0201302. [PMID: 30048509 PMCID: PMC6062085 DOI: 10.1371/journal.pone.0201302] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Accepted: 05/28/2018] [Indexed: 12/31/2022] Open
Abstract
We propose a mathematical and computational model that captures the stimulus-generated Ca2+ transients in the C. elegans ASH sensory neuron. The rationale is to develop a tool that will enable a cross-talk between modeling and experiments, using modeling results to guide targeted experimental efforts. The model is built based on biophysical events and molecular cascades known to unfold as part of neurons' Ca2+ homeostasis mechanism, as well as on Ca2+ signaling events. The state of ion channels is described by their probability of being activated or inactivated, and the remaining molecular states are based on biochemically defined kinetic equations or known biochemical motifs. We estimate the parameters of the model using experimental data of hyperosmotic stimulus-evoked Ca2+ transients detected with a FRET sensor in young and aged worms, unstressed and exposed to oxidative stress. We use a hybrid optimization method composed of a multi-objective genetic algorithm and nonlinear least-squares to estimate the model parameters. We first obtain the model parameters for young unstressed worms. Next, we use these values of the parameters as a starting point to identify the model parameters for stressed and aged worms. We show that the model, in combination with experimental data, corroborates literature results. In addition, we demonstrate that our model can be used to predict ASH response to complex combinations of stimulation pulses. The proposed model includes for the first time the ASH Ca2+ dynamics observed during both "on" and "off" responses. This mathematical and computational effort is the first to propose a dynamic model of the Ca2+ transients' mechanism in C. elegans neurons, based on biochemical pathways of the cell's Ca2+ homeostasis machinery. We believe that the proposed model can be used to further elucidate the Ca2+ dynamics of a key C. elegans neuron, to guide future experiments on C. elegans neurobiology, and to pave the way for the development of more mathematical models for neuronal Ca2+ dynamics.
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Affiliation(s)
- Ehsan Mirzakhalili
- Mechanical Engineering Department, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Bogdan I. Epureanu
- Mechanical Engineering Department, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Eleni Gourgou
- Mechanical Engineering Department, University of Michigan, Ann Arbor, Michigan, United States of America
- Department of Internal Medicine, Division of Geriatrics, Medical School, University of Michigan, Ann Arbor, Michigan, United States of America
- * E-mail:
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9
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Gribble KE, Mark Welch DB. Genome-wide transcriptomics of aging in the rotifer Brachionus manjavacas, an emerging model system. BMC Genomics 2017; 18:217. [PMID: 28249563 PMCID: PMC5333405 DOI: 10.1186/s12864-017-3540-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Accepted: 02/02/2017] [Indexed: 12/22/2022] Open
Abstract
Background Understanding gene expression changes over lifespan in diverse animal species will lead to insights to conserved processes in the biology of aging and allow development of interventions to improve health. Rotifers are small aquatic invertebrates that have been used in aging studies for nearly 100 years and are now re-emerging as a modern model system. To provide a baseline to evaluate genetic responses to interventions that change health throughout lifespan and a framework for new hypotheses about the molecular genetic mechanisms of aging, we examined the transcriptome of an asexual female lineage of the rotifer Brachionus manjavacas at five life stages: eggs, neonates, and early-, late-, and post-reproductive adults. Results There are widespread shifts in gene expression over the lifespan of B. manjavacas; the largest change occurs between neonates and early reproductive adults and is characterized by down-regulation of developmental genes and up-regulation of genes involved in reproduction. The expression profile of post-reproductive adults was distinct from that of other life stages. While few genes were significantly differentially expressed in the late- to post-reproductive transition, gene set enrichment analysis revealed multiple down-regulated pathways in metabolism, maintenance and repair, and proteostasis, united by genes involved in mitochondrial function and oxidative phosphorylation. Conclusions This study provides the first examination of changes in gene expression over lifespan in rotifers. We detected differential expression of many genes with human orthologs that are absent in Drosophila and C. elegans, highlighting the potential of the rotifer model in aging studies. Our findings suggest that small but coordinated changes in expression of many genes in pathways that integrate diverse functions drive the aging process. The observation of simultaneous declines in expression of genes in multiple pathways may have consequences for health and longevity not detected by single- or multi-gene knockdown in otherwise healthy animals. Investigation of subtle but genome-wide change in these pathways during aging is an important area for future study. Electronic supplementary material The online version of this article (doi:10.1186/s12864-017-3540-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Kristin E Gribble
- Josephine Bay Paul Center for Comparative Molecular Biology and Evolution, Marine Biological Laboratory, Woods Hole, MA, 02543, USA
| | - David B Mark Welch
- Josephine Bay Paul Center for Comparative Molecular Biology and Evolution, Marine Biological Laboratory, Woods Hole, MA, 02543, USA.
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10
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Frazier HN, Maimaiti S, Anderson KL, Brewer LD, Gant JC, Porter NM, Thibault O. Calcium's role as nuanced modulator of cellular physiology in the brain. Biochem Biophys Res Commun 2016; 483:981-987. [PMID: 27553276 DOI: 10.1016/j.bbrc.2016.08.105] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Revised: 08/04/2016] [Accepted: 08/18/2016] [Indexed: 12/22/2022]
Abstract
Neuroscientists studying normal brain aging, spinal cord injury, Alzheimer's disease (AD) and other neurodegenerative diseases have focused considerable effort on carefully characterizing intracellular perturbations in calcium dynamics or levels. At the cellular level, calcium is known for controlling life and death and orchestrating most events in between. For many years, intracellular calcium has been recognized as an essential ion associated with nearly all cellular functions from cell growth to degeneration. Often the emphasis is on the negative impact of calcium dysregulation and the typical worse-case-scenario leading inevitably to cell death. However, even high amplitude calcium transients, when executed acutely, can alter neuronal communication and synaptic strength in positive ways, without necessarily killing neurons. Here, we focus on the evidence that calcium has a subtle and distinctive role in shaping and controlling synaptic events that underpin neuronal communication and that these subtle changes in aging or AD may contribute to cognitive decline. We emphasize that calcium imaging in dendritic components is ultimately necessary to directly test for the presence of age- or disease-associated alterations during periods of synaptic activation.
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Affiliation(s)
- Hilaree N Frazier
- UKMC, MS-313, Department of Pharmacology and Nutritional Sciences, University of Kentucky Medical Center, 800 Rose Street, Lexington, KY 40536, USA
| | - Shaniya Maimaiti
- UKMC, MS-313, Department of Pharmacology and Nutritional Sciences, University of Kentucky Medical Center, 800 Rose Street, Lexington, KY 40536, USA
| | - Katie L Anderson
- UKMC, MS-313, Department of Pharmacology and Nutritional Sciences, University of Kentucky Medical Center, 800 Rose Street, Lexington, KY 40536, USA
| | - Lawrence D Brewer
- UKMC, MS-313, Department of Pharmacology and Nutritional Sciences, University of Kentucky Medical Center, 800 Rose Street, Lexington, KY 40536, USA
| | - John C Gant
- UKMC, MS-313, Department of Pharmacology and Nutritional Sciences, University of Kentucky Medical Center, 800 Rose Street, Lexington, KY 40536, USA
| | - Nada M Porter
- UKMC, MS-313, Department of Pharmacology and Nutritional Sciences, University of Kentucky Medical Center, 800 Rose Street, Lexington, KY 40536, USA
| | - Olivier Thibault
- UKMC, MS-313, Department of Pharmacology and Nutritional Sciences, University of Kentucky Medical Center, 800 Rose Street, Lexington, KY 40536, USA.
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11
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Proft J, Weiss N. Looking for answers to L-type calcium channels in the ageing brain (Commentary on Zanoset al.). Eur J Neurosci 2015; 42:2496-8. [DOI: 10.1111/ejn.13017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Juliane Proft
- Institute of Organic Chemistry and Biochemistry; Academy of Sciences of the Czech Republic; Prague Czech Republic
| | - Norbert Weiss
- Institute of Organic Chemistry and Biochemistry; Academy of Sciences of the Czech Republic; Prague Czech Republic
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12
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Proft J, Weiss N. T-type Ca(2+) channels: New players in the aging brain. Commun Integr Biol 2014; 7:e28424. [PMID: 24748914 PMCID: PMC3990594 DOI: 10.4161/cib.28424] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2014] [Accepted: 03/03/2014] [Indexed: 11/19/2022] Open
Abstract
Perhaps one of the most remarkable features of T-type calcium channels is their low-threshold of activation that makes these channels important candidates for calcium entry near the resting membrane potential of neurons. Hence, they mediate low-threshold burst discharges that occur during different forms of neuronal rhythmogenesis, but play also important roles in sensory transmission, as well as hormone and neurotransmitter release. Additionally, they have been implicated in an increasing number of neuronal pathologies including neuropathy, autism spectrum disorders and some forms of epilepsy. More recently, an implication of T-type calcium channel in the processing of Amyloid Precursor Protein was documented, with possible implication in the pathogenesis of Alzheimer’s disease.
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Affiliation(s)
- Juliane Proft
- Institute of Organic Chemistry and Biochemistry; Academy of Sciences of the Czech Republic; Prague, Czech Republic
| | - Norbert Weiss
- Institute of Organic Chemistry and Biochemistry; Academy of Sciences of the Czech Republic; Prague, Czech Republic
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13
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Nikoletopoulou V, Tavernarakis N. Calcium homeostasis in aging neurons. Front Genet 2012; 3:200. [PMID: 23060904 PMCID: PMC3462315 DOI: 10.3389/fgene.2012.00200] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Accepted: 09/19/2012] [Indexed: 11/13/2022] Open
Abstract
The nervous system becomes increasingly vulnerable to insults and prone to dysfunction during aging. Age-related decline of neuronal function is manifested by the late onset of many neurodegenerative disorders, as well as by reduced signaling and processing capacity of individual neuron populations. Recent findings indicate that impairment of Ca(2+) homeostasis underlies the increased susceptibility of neurons to damage, associated with the aging process. However, the impact of aging on Ca(2+) homeostasis in neurons remains largely unknown. Here, we survey the molecular mechanisms that mediate neuronal Ca(2+) homeostasis and discuss the impact of aging on their efficacy. To address the question of how aging impinges on Ca(2+) homeostasis, we consider potential nodes through which mechanisms regulating Ca(2+) levels interface with molecular pathways known to influence the process of aging and senescent decline. Delineation of this crosstalk would facilitate the development of interventions aiming to fortify neurons against age-associated functional deterioration and death by augmenting Ca(2+) homeostasis.
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Affiliation(s)
- Vassiliki Nikoletopoulou
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology - Hellas Heraklion, Crete, Greece
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14
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Kawamoto EM, Vivar C, Camandola S. Physiology and pathology of calcium signaling in the brain. Front Pharmacol 2012; 3:61. [PMID: 22518105 PMCID: PMC3325487 DOI: 10.3389/fphar.2012.00061] [Citation(s) in RCA: 138] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2012] [Accepted: 03/26/2012] [Indexed: 12/31/2022] Open
Abstract
Calcium (Ca(2+)) plays fundamental and diversified roles in neuronal plasticity. As second messenger of many signaling pathways, Ca(2+) as been shown to regulate neuronal gene expression, energy production, membrane excitability, synaptogenesis, synaptic transmission, and other processes underlying learning and memory and cell survival. The flexibility of Ca(2+) signaling is achieved by modifying cytosolic Ca(2+) concentrations via regulated opening of plasma membrane and subcellular Ca(2+) sensitive channels. The spatiotemporal patterns of intracellular Ca(2+) signals, and the ultimate cellular biological outcome, are also dependent upon termination mechanism, such as Ca(2+) buffering, extracellular extrusion, and intra-organelle sequestration. Because of the central role played by Ca(2+) in neuronal physiology, it is not surprising that even modest impairments of Ca(2+) homeostasis result in profound functional alterations. Despite their heterogeneous etiology neurodegenerative disorders, as well as the healthy aging process, are all characterized by disruption of Ca(2+) homeostasis and signaling. In this review we provide an overview of the main types of neuronal Ca(2+) channels and their role in neuronal plasticity. We will also discuss the participation of Ca(2+) signaling in neuronal aging and degeneration.
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Affiliation(s)
- Elisa Mitiko Kawamoto
- Laboratory of Neurosciences, National Institute on Aging, Intramural Research ProgramBaltimore, MD, USA
| | - Carmen Vivar
- Laboratory of Neurosciences, National Institute on Aging, Intramural Research ProgramBaltimore, MD, USA
| | - Simonetta Camandola
- Laboratory of Neurosciences, National Institute on Aging, Intramural Research ProgramBaltimore, MD, USA
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15
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Ovsepian SV, Dolly JO, Zaborszky L. Intrinsic voltage dynamics govern the diversity of spontaneous firing profiles in basal forebrain noncholinergic neurons. J Neurophysiol 2012; 108:406-18. [PMID: 22496531 DOI: 10.1152/jn.00642.2011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Spontaneous firing and behavior-related changes in discharge profiles of basal forebrain (BF) neurons are well documented, albeit the mechanisms underlying the variety of activity modes and intermodal transitions remain elusive. With the use of cell-attached recordings, this study identifies a range of spiking patterns in diagonal band Broca (DBB) noncholinergic cells of rats and tentatively categorizes them into low-rate random, tonic, and cluster firing activities. It demonstrates further that the multiplicity of discharge profiles is sustained intrinsically and persists after blockade of glutamate-, glycine/GABA-, and cholinergic synaptic inputs. Stimulation of muscarinic receptors, blockade of voltage-gated Ca(2+)-, and small conductance (SK) Ca(2+)-activated K(+) currents as well as chelating of intracellular Ca(2+) concentration accelerate low-rate random and tonic firing and favor transition of neurons into cluster firing mode. A similar trend towards higher discharge rates with switch of neurons into cluster firing has been revealed by activation of neuropeptide Y (NPY) receptors with the NPY or NPY(1) receptor agonist [Leu(31),Pro(34)]-NPY. Whole cell current-clamp analysis demonstrates that the variety of spiking modes and intermodal transitions could be induced within the same neuronal population by injection of bias depolarizing or hyperpolarizing currents. Taken together, these data demonstrate the intrinsic and highly variable character of regenerative firing in BF noncholinergic cells, subject to powerful modulation by classical neurotransmitters, NPY, and small membrane currents.
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Affiliation(s)
- Saak V Ovsepian
- Center for Molecular and Behavioral Neuroscience, Rutgers, The State University of New Jersey, Newark, New Jersey, USA.
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16
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Decuypere JP, Monaco G, Missiaen L, De Smedt H, Parys JB, Bultynck G. IP(3) Receptors, Mitochondria, and Ca Signaling: Implications for Aging. J Aging Res 2011; 2011:920178. [PMID: 21423550 PMCID: PMC3056293 DOI: 10.4061/2011/920178] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2010] [Revised: 12/23/2010] [Accepted: 01/05/2011] [Indexed: 12/21/2022] Open
Abstract
The tight interplay between endoplasmic-reticulum-(ER-) and mitochondria-mediated Ca(2+) signaling is a key determinant of cellular health and cellular fate through the control of apoptosis and autophagy. Proteins that prevent or promote apoptosis and autophagy can affect intracellular Ca(2+) dynamics and homeostasis through binding and modulation of the intracellular Ca(2+)-release and Ca(2+)-uptake mechanisms. During aging, oxidative stress becomes an additional factor that affects ER and mitochondrial function and thus their role in Ca(2+) signaling. Importantly, mitochondrial dysfunction and sustained mitochondrial damage are likely to underlie part of the aging process. In this paper, we will discuss the different mechanisms that control intracellular Ca(2+) signaling with respect to apoptosis and autophagy and review how these processes are affected during aging through accumulation of reactive oxygen species.
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Affiliation(s)
- Jean-Paul Decuypere
- Laboratory of Molecular and Cellular Signaling, Department of Molecular and Cellular Biology, K.U.Leuven, Campus Gasthuisberg O/N-1, Herestraat 49, Bus 802, 3000 Leuven, Belgium
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17
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Srinivasan S, Ausk BJ, Prasad J, Threet D, Bain SD, Richardson TS, Gross TS. Rescuing loading induced bone formation at senescence. PLoS Comput Biol 2010; 6:e1000924. [PMID: 20838577 PMCID: PMC2936512 DOI: 10.1371/journal.pcbi.1000924] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2010] [Accepted: 08/09/2010] [Indexed: 01/27/2023] Open
Abstract
The increasing incidence of osteoporosis worldwide requires anabolic treatments that are safe, effective, and, critically, inexpensive given the prevailing overburdened health care systems. While vigorous skeletal loading is anabolic and holds promise, deficits in mechanotransduction accrued with age markedly diminish the efficacy of readily complied, exercise-based strategies to combat osteoporosis in the elderly. Our approach to explore and counteract these age-related deficits was guided by cellular signaling patterns across hierarchical scales and by the insight that cell responses initiated during transient, rare events hold potential to exert high-fidelity control over temporally and spatially distant tissue adaptation. Here, we present an agent-based model of real-time Ca(2+)/NFAT signaling amongst bone cells that fully described periosteal bone formation induced by a wide variety of loading stimuli in young and aged animals. The model predicted age-related pathway alterations underlying the diminished bone formation at senescence, and hence identified critical deficits that were promising targets for therapy. Based upon model predictions, we implemented an in vivo intervention and show for the first time that supplementing mechanical stimuli with low-dose Cyclosporin A can completely rescue loading induced bone formation in the senescent skeleton. These pre-clinical data provide the rationale to consider this approved pharmaceutical alongside mild physical exercise as an inexpensive, yet potent therapy to augment bone mass in the elderly. Our analyses suggested that real-time cellular signaling strongly influences downstream bone adaptation to mechanical stimuli, and quantification of these otherwise inaccessible, transient events in silico yielded a novel intervention with clinical potential.
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Affiliation(s)
- Sundar Srinivasan
- Department of Orthopedics and Sports Medicine, University of Washington, Seattle, Washington, United States of America.
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18
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Kumar A, Bodhinathan K, Foster TC. Susceptibility to Calcium Dysregulation during Brain Aging. Front Aging Neurosci 2009; 1:2. [PMID: 20552053 PMCID: PMC2874411 DOI: 10.3389/neuro.24.002.2009] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2009] [Accepted: 10/27/2009] [Indexed: 01/06/2023] Open
Abstract
Calcium (Ca(2+)) is a highly versatile intracellular signaling molecule that is essential for regulating a variety of cellular and physiological processes ranging from fertilization to programmed cell death. Research has provided ample evidence that brain aging is associated with altered Ca(2+) homeostasis. Much of the work has focused on the hippocampus, a brain region critically involved in learning and memory, which is particularly susceptible to dysfunction during senescence. The current review takes a broader perspective, assessing age-related changes in Ca(2+) sources, Ca(2+) sequestration, and Ca(2+) binding proteins throughout the nervous system. The nature of altered Ca(2+) homeostasis is cell specific and may represent a deficit or a compensatory mechanism, producing complex patterns of impaired cellular function. Incorporating the knowledge of the complexity of age-related alterations in Ca(2+) homeostasis will positively shape the development of highly effective therapeutics to treat brain disorders.
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Affiliation(s)
- Ashok Kumar
- Department of Neuroscience, McKnight Brain Institute, University of Florida Gainesville, FL, USA
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19
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Murchison D, McDermott AN, Lasarge CL, Peebles KA, Bizon JL, Griffith WH. Enhanced calcium buffering in F344 rat cholinergic basal forebrain neurons is associated with age-related cognitive impairment. J Neurophysiol 2009; 102:2194-207. [PMID: 19675291 DOI: 10.1152/jn.00301.2009] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Alterations in neuronal Ca(2+) homeostasis are important determinants of age-related cognitive impairment. We examined the Ca(2+) influx, buffering, and electrophysiology of basal forebrain neurons in adult, middle-aged, and aged male F344 behaviorally assessed rats. Middle-aged and aged rats were characterized as cognitively impaired or unimpaired by water maze performance relative to young cohorts. Patch-clamp experiments were conducted on neurons acutely dissociated from medial septum/nucleus of the diagonal band with post hoc identification of phenotypic marker mRNA using single-cell RT-PCR. We measured whole cell calcium and barium currents and dissected these currents using pharmacological agents. We combined Ca(2+) current recording with Ca(2+)-sensitive ratiometric microfluorimetry to measure Ca(2+) buffering. Additionally, we sought changes in neuronal firing properties using current-clamp recording. There were no age- or cognition-related changes in the amplitudes or fractional compositions of the whole cell Ca(2+) channel currents. However, Ca(2+) buffering was significantly enhanced in cholinergic neurons from aged cognitively impaired rats. Moreover, increased Ca(2+) buffering was present in middle-aged rats that were not cognitively impaired. Firing properties were largely unchanged with age or cognitive status, except for an increase in the slow afterhyperpolarization in aged cholinergic neurons, independent of cognitive status. Furthermore, acutely dissociated basal forebrain neurons in which choline acetyltransferase mRNA was detected had the electrophysiological profiles of identified cholinergic neurons. We conclude that enhanced Ca(2+) buffering by cholinergic basal forebrain neurons may be important during aging.
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Affiliation(s)
- David Murchison
- 1Department of Neuroscience and Experimental Therapeutics, Texas A&M Health Science Center, College Station, Texas77843-1114, USA
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20
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Abstract
The endoplasmic reticulum (ER) is a multifunctional organelle which co-ordinates protein folding, lipid biosynthesis, calcium storage and release. Perturbations that disrupt ER homeostasis lead to ER stress and upregulation of a signaling pathway called the unfolded protein response (UPR). The UPR while robust in young animals appears to be compromised with aging; many of the components of the UPR have decreased expression and activity with age. There is also considerable evidence of oxidative damage. There are suggestions that an impaired UPR may contribute to the acceleration of neurodegenerative disorders.
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Affiliation(s)
- Nirinjini Naidoo
- University of Pennsylvania School of Medicine, Center for Sleep and Respiratory Neurobiology, Philadelphia, PA 19104, USA.
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21
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Puzianowska-Kuznicka M, Kuznicki J. The ER and ageing II: calcium homeostasis. Ageing Res Rev 2009; 8:160-72. [PMID: 19427411 DOI: 10.1016/j.arr.2009.05.002] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2009] [Revised: 04/30/2009] [Accepted: 05/01/2009] [Indexed: 11/29/2022]
Abstract
Increase in intracellular Ca(2+) concentration occurs by Ca(2+) influx through the plasma membrane and by Ca(2+) release from intracellular stores. The ER is the most important Ca(2+) store. Its stress, characterized by the impairment of Ca(2+) homeostasis and by the accumulation of misfolded proteins, can be induced by different factors. In turn, it induces defense mechanisms such as unfolded protein response, and when it is severe and prolonged, activation of the apoptotic pathway. Damage to the ER, impairment of its function, and a decreased level of its Ca(2+)-handling proteins might all play a role in physiological ageing by handicapping the ER stress response. Thus, healthy ageing is accompanied by subtle alterations of Ca(2+) homeostasis and signaling, including alterations in the ER Ca(2+) load and release. The expression and/or function of ryanodine receptors, IP3 receptors, and SERCA Ca(2+) pumps located in the ER membrane, and Ca(2+)-binding proteins within ER lumen all seem to be affected in aged cells. Data are presented on age-dependent, tissue-specific changes in ER-related Ca(2+) homeostasis in skeletal, cardiac and smooth muscles, as well as in the nervous and immune systems. Disturbances of Ca(2+) homeostasis and of signaling are potential targets for intervention in aged humans.
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22
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Castaldo P, Cataldi M, Magi S, Lariccia V, Arcangeli S, Amoroso S. Role of the mitochondrial sodium/calcium exchanger in neuronal physiology and in the pathogenesis of neurological diseases. Prog Neurobiol 2008; 87:58-79. [PMID: 18952141 DOI: 10.1016/j.pneurobio.2008.09.017] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2008] [Revised: 09/23/2008] [Accepted: 09/29/2008] [Indexed: 11/26/2022]
Abstract
In neurons, as in other excitable cells, mitochondria extrude Ca(2+) ions from their matrix in exchange with cytosolic Na(+) ions. This exchange is mediated by a specific transporter located in the inner mitochondrial membrane, the mitochondrial Na(+)/Ca(2+) exchanger (NCX(mito)). The stoichiometry of NCX(mito)-operated Na(+)/Ca(2+) exchange has been the subject of a long controversy, but evidence of an electrogenic 3 Na(+)/1 Ca(2+) exchange is increasing. Although the molecular identity of NCX(mito) is still undetermined, data obtained in our laboratory suggest that besides the long-sought and as yet unfound mitochondrial-specific NCX, the three isoforms of plasmamembrane NCX can contribute to NCX(mito) in neurons and astrocytes. NCX(mito) has a role in controlling neuronal Ca(2+) homeostasis and neuronal bioenergetics. Indeed, by cycling the Ca(2+) ions captured by mitochondria back to the cytosol, NCX(mito) determines a shoulder in neuronal [Ca(2+)](c) responses to neurotransmitters and depolarizing stimuli which may then outlast stimulus duration. This persistent NCX(mito)-dependent Ca(2+) release has a role in post-tetanic potentiation, a form of short-term synaptic plasticity. By controlling [Ca(2+)](m) NCX(mito) regulates the activity of the Ca(2+)-sensitive enzymes pyruvate-, alpha-ketoglutarate- and isocitrate-dehydrogenases and affects the activity of the respiratory chain. Convincing experimental evidence suggests that supraphysiological activation of NCX(mito) contributes to neuronal cell death in the ischemic brain and, in epileptic neurons coping with seizure-induced ion overload, reduces the ability to reestablish normal ionic homeostasis. These data suggest that NCX(mito) could represent an important target for the development of new neurological drugs.
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Affiliation(s)
- P Castaldo
- Department of Neuroscience, Section of Pharmacology, Università Politecnica delle Marche, Via Tronto 10/A, 60020 Torrette di Ancona, Ancona, Italy
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23
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Thibault O, Gant JC, Landfield PW. Expansion of the calcium hypothesis of brain aging and Alzheimer's disease: minding the store. Aging Cell 2007; 6:307-17. [PMID: 17465978 PMCID: PMC1974776 DOI: 10.1111/j.1474-9726.2007.00295.x] [Citation(s) in RCA: 287] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Evidence accumulated over more than two decades has implicated Ca2+ dysregulation in brain aging and Alzheimer's disease (AD), giving rise to the Ca2+ hypothesis of brain aging and dementia. Electrophysiological, imaging, and behavioral studies in hippocampal or cortical neurons of rodents and rabbits have revealed aging-related increases in the slow afterhyperpolarization, Ca2+ spikes and currents, Ca2+ transients, and L-type voltage-gated Ca2+ channel (L-VGCC) activity. Several of these changes have been associated with age-related deficits in learning or memory. Consequently, one version of the Ca2+ hypothesis has been that increased L-VGCC activity drives many of the other Ca2+-related biomarkers of hippocampal aging. In addition, other studies have reported aging- or AD model-related alterations in Ca2+ release from ryanodine receptors (RyR) on intracellular stores. The Ca2+-sensitive RyR channels amplify plasmalemmal Ca2+ influx by the mechanism of Ca2+-induced Ca2+ release (CICR). Considerable evidence indicates that a preferred functional link is present between L-VGCCs and RyRs which operate in series in heart and some brain cells. Here, we review studies implicating RyRs in altered Ca2+ regulation in cell toxicity, aging, and AD. A recent study from our laboratory showed that increased CICR plays a necessary role in the emergence of Ca2+-related biomarkers of aging. Consequently, we propose an expanded L-VGCC/Ca2+ hypothesis, in which aging/pathological changes occur in both L-type Ca2+ channels and RyRs, and interact to abnormally amplify Ca2+ transients. In turn, the increased transients result in dysregulation of multiple Ca2+-dependent processes and, through somewhat different pathways, in accelerated functional decline during aging and AD.
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Affiliation(s)
- Olivier Thibault
- Department of Molecular and Biomedical Pharmacology, University of Kentucky, University of Kentucky Medical Center, Lexington, KY 40536, USA
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24
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Buchholz JN, Behringer EJ, Pottorf WJ, Pearce WJ, Vanterpool CK. Age-dependent changes in Ca2+ homeostasis in peripheral neurones: implications for changes in function. Aging Cell 2007; 6:285-96. [PMID: 17517039 PMCID: PMC1974774 DOI: 10.1111/j.1474-9726.2007.00298.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Calcium ions represent universal second messengers within neuronal cells integrating multiple cellular functions, such as release of neurotransmitters, gene expression, proliferation, excitability, and regulation of cell death or apoptotic pathways. The magnitude, duration and shape of stimulation-evoked intracellular calcium ([Ca2+]i) transients are determined by a complex interplay of mechanisms that modulate stimulation-evoked rises in [Ca2+]i that occur with normal neuronal function. Disruption of any of these mechanisms may have implications for the function and health of peripheral neurones during the aging process. This review focuses on the impact of advancing age on the overall function of peripheral adrenergic neurones and how these changes in function may be linked to age-related changes in modulation of [Ca2+]i regulation. The data in this review suggest that normal aging in peripheral autonomic neurones is a subtle process and does not always result in dramatic deterioration in their function. We present studies that support the idea that in order to maintain cell viability peripheral neurones are able to compensate for an age-related decline in the function of at least one of the neuronal calcium-buffering systems, smooth endoplasmic reticulum calcium ATPases, by increased function of other calcium-buffering systems, namely, the mitochondria and plasmalemma calcium extrusion. Increased mitochondrial calcium uptake may represent a 'weak point' in cellular compensation as this over time may contribute to cell death. In addition, we present more recent studies on [Ca2+]i regulation in the form of the modulation of release of calcium from smooth endoplasmic reticulum calcium stores. These studies suggest that the contribution of the release of calcium from smooth endoplasmic reticulum calcium stores is altered with age through a combination of altered ryanodine receptor levels and modulation of these receptors by neuronal nitric oxide containing neurones.
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Affiliation(s)
- John N Buchholz
- Department of Physiology and Pharmacology, Loma Linda University, School of Medicine, Loma Linda, CA 92350, USA.
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25
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Toescu EC, Verkhratsky A. The importance of being subtle: small changes in calcium homeostasis control cognitive decline in normal aging. Aging Cell 2007; 6:267-73. [PMID: 17517038 DOI: 10.1111/j.1474-9726.2007.00296.x] [Citation(s) in RCA: 140] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Aging is a complex, multifactorial process. One of the features of normal aging of the brain is a decline in cognitive functions and much experimental attention has been devoted to understanding this process. Evidence accumulated in the last decade indicates that such functional changes are not due to gross morphological alterations, but to subtle functional modification of synaptic connectivity and intracellular signalling and metabolism. Such synaptic modifications are compatible with a normal level of activity and allow the maintenance of a certain degree of functional reserve. This is in contrast to the changes in various neurodegenerative diseases, characterized by significant neuronal loss and dramatic and irreversible functional deficit. This whole special issue has been initiated with the intention of focusing on the processes of normal brain aging. In this review, we present data that shows how subtle changes in Ca(2+) homeostasis or in the state of various Ca(2+)-dependent processes or molecules, which occur in aging can have significant functional consequences.
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Affiliation(s)
- Emil C Toescu
- Department of Physiology, Division of Medical Sciences, The Medical School, University of Birmingham, Birmingham B15 2TT, UK.
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26
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Fernandes D, Zaidi A, Bean J, Hui D, Michaelis ML. RNA--induced silencing of the plasma membrane Ca2+-ATPase 2 in neuronal cells: effects on Ca2+ homeostasis and cell viability. J Neurochem 2007; 102:454-65. [PMID: 17488275 DOI: 10.1111/j.1471-4159.2007.04592.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Intraneuronal calcium ([Ca(2+)](i)) regulation is altered in aging brain, possibly because of the changes in critical Ca(2+) transporters. We previously reported that the levels of the plasma membrane Ca(2+)-ATPase (PMCA) and the V(max) for enzyme activity are significantly reduced in synaptic membranes in aging rat brain. The goal of these studies was to use RNA(i) techniques to suppress expression of a major neuronal isoform, PMCA2, in neurons in culture to determine the potential functional consequences of a decrease in PMCA activity. Embryonic rat brain neurons and SH-SY5Y neuroblastoma cells were transfected with in vitro--transcribed short interfering RNA or a short hairpin RNA expressing vector, respectively, leading to 80% suppression of PMCA2 expression within 48 h. Fluorescence ratio imaging of free [Ca(2+)](i) revealed that primary neurons with reduced PMCA2 expression had higher basal [Ca(2+)](i), slower recovery from KCl-induced Ca(2+) transients, and incomplete return to pre-stimulation Ca(2+) levels. Primary neurons and SH-SY5Y cells with PMCA2 suppression both exhibited significantly greater vulnerability to the toxicity of various stresses. Our results indicate that a loss of PMCA such as occurs in aging brain likely leads to subtle disruptions in normal Ca(2+) signaling and enhanced susceptibility to stresses that can alter the regulation of Ca(2+) homeostasis.
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27
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del Corsso C, Ostrovskaya O, McAllister CE, Murray K, Hatton WJ, Gurney AM, Spencer NJ, Wilson SM. Effects of aging on Ca2+ signaling in murine mesenteric arterial smooth muscle cells. Mech Ageing Dev 2006; 127:315-23. [PMID: 16413046 DOI: 10.1016/j.mad.2005.12.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2005] [Revised: 11/23/2005] [Accepted: 12/07/2005] [Indexed: 11/21/2022]
Abstract
Pathophysiological changes in arterial smooth muscle structure and function occur with aging and there are a number of reports illustrating reductions in vascular responsiveness with aging. While much is known about arterial remodeling and functional adaptations with aging, very little is known about the biophysical adaptations in individual arterial myocytes. Cytosolic Ca2+ signaling, involving activation of L-type Ca2+ channels on the plasma membrane as well as InsP3 and ryanodine receptors on the sarcoplasmic reticulum, is integral to vascular tone and reactivity. Thus, we tested the hypothesis that aging results in reductions in the functional expression of L-type channels and temporal aspects of ryanodine receptor and InsP3 receptor Ca2+ signaling, in mesenteric arterial smooth muscle cells isolated from 6 and 30 months old C57Bl/6 mice. Comparisons of L-type current activity were made using dialyzed, whole-cell voltage-clamp techniques and Ba2+ as charge carrier. Ca2+ signaling was measured using fura-2 fluorescence microscopy techniques. Cell morphological changes were also investigated using electrophysiological and immunocytochemical approaches. The amplitudes of L-type Ca2+ currents were increased in older mice, but this was associated with membrane surface area increases of approximately 50%, due to increases in cell length not cell width. Consequently, L-type Ca2+ current densities were preserved with age, indicating functional channel expression was unchanged. In contrast, aging was associated with decrements in Ca2+ signaling in response to either ryanodine receptor stimulation by caffeine or InsP3 receptor activation with phenylephrine. These changes with aging may be related to the previously reported depression in myogenic reactivity.
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Affiliation(s)
- Cristiane del Corsso
- Department of Physiology, University of Nevada School of Medicine, Reno, NV 89557, USA
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28
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Lin DT, Wu J, Holstein D, Upadhyay G, Rourk W, Muller E, Lechleiter JD. Ca2+ signaling, mitochondria and sensitivity to oxidative stress in aging astrocytes. Neurobiol Aging 2005; 28:99-111. [PMID: 16359757 DOI: 10.1016/j.neurobiolaging.2005.11.004] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2005] [Revised: 10/31/2005] [Accepted: 11/09/2005] [Indexed: 11/30/2022]
Abstract
Age-related changes in astrocytes that could potentially affect neuroprotection have been largely unexplored. To test whether astrocyte function was diminished during the aging process, we examined cell growth, Ca2+ signaling, mitochondrial membrane potential (DeltaPsi) and neuroprotection of NGF-differentiated PC12 cells. We observed that cell growth was significantly slower for astrocytes cultured from old (26-29 months) mice as compared to young (4-6 months) mice. DeltaPsis in old astrocytes were also more depolarized (lower) than in young astrocytes and old astrocytes showed greater sensitivity to the oxidant tert-butyl hydrogen peroxide (t-BuOOH). ATP-induced Ca2+ responses in old astrocytes were consistently larger in amplitude and more frequently oscillatory than in young astrocytes, which may be attributable to lower mitochondrial Ca2+ sequestration. Finally, NGF-differentiated PC12 cells that were co-cultured with old astrocytes were significantly more sensitive to t-BuOOH treatment than co-cultures of NGF-differentiated PC12 cells with young astrocytes. Together, these data demonstrate that astrocyte physiology is significantly altered during the aging process and that the astrocyte's ability to protect neurons is compromised.
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Affiliation(s)
- Da-Ting Lin
- Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229-3900, United States
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29
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Ismailov I, Kalikulov D, Inoue T, Friedlander MJ. The kinetic profile of intracellular calcium predicts long-term potentiation and long-term depression. J Neurosci 2005; 24:9847-61. [PMID: 15525769 PMCID: PMC6730235 DOI: 10.1523/jneurosci.0738-04.2004] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Efficiency of synaptic transmission within the neocortex is regulated throughout life by experience and activity. Periods of correlated or uncorrelated presynaptic and postsynaptic activity lead to enduring changes in synaptic efficiency [long-term potentiation (LTP) and long-term depression (LTD), respectively]. The initial plasticity triggering event is thought to be a precipitous rise in postsynaptic intracellular calcium, with higher levels inducing LTP and more moderate levels inducing LTD. We used a pairing protocol in visual cortical brain slices from young guinea pigs with whole-cell recording and calcium imaging to compare the kinetic profiles of calcium signals generated in response to individual pairings along with the cumulative calcium wave and plasticity outcome. The identical pairing protocol applied to layer 2/3 pyramidal neurons results in different plasticity outcomes between cells. These differences are not attributable to variations in the conditioning protocol, cellular properties, inter-animal variability, animal age, differences in spike timing between the synaptic response and spikes, washout of plasticity factors, recruitment of inhibition, or activation of different afferents. The different plasticity outcomes are reliably predicted by individual intracellular calcium transients in the dendrites after the first few pairings. In addition to the differences in the individual calcium transients, the cumulative calcium wave that spreads to the soma also has a different profile for cells that undergo LTP versus LTD. We conclude that there are biological differences between like-type cells in the dendritic calcium signals generated by coincident synaptic input and spiking that determine the sign of the plasticity response after brief associations.
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Affiliation(s)
- Iskander Ismailov
- Department of Neurobiology and the Civitan International Research Center and The Evelyn F. McKnight Brain Institute, The University of Alabama at Birmingham, Birmingham, Alabama 35294-0021, USA
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30
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Verkhratsky A. Physiology and Pathophysiology of the Calcium Store in the Endoplasmic Reticulum of Neurons. Physiol Rev 2005; 85:201-79. [PMID: 15618481 DOI: 10.1152/physrev.00004.2004] [Citation(s) in RCA: 561] [Impact Index Per Article: 29.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The endoplasmic reticulum (ER) is the largest single intracellular organelle, which is present in all types of nerve cells. The ER is an interconnected, internally continuous system of tubules and cisterns, which extends from the nuclear envelope to axons and presynaptic terminals, as well as to dendrites and dendritic spines. Ca2+release channels and Ca2+pumps residing in the ER membrane provide for its excitability. Regulated ER Ca2+release controls many neuronal functions, from plasmalemmal excitability to synaptic plasticity. Enzymatic cascades dependent on the Ca2+concentration in the ER lumen integrate rapid Ca2+signaling with long-lasting adaptive responses through modifications in protein synthesis and processing. Disruptions of ER Ca2+homeostasis are critically involved in various forms of neuropathology.
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Affiliation(s)
- Alexei Verkhratsky
- The University of Manchester, Faculty of Biological Sciences, United Kingdom.
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31
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Murchison D, Zawieja DC, Griffith WH. Reduced mitochondrial buffering of voltage-gated calcium influx in aged rat basal forebrain neurons. Cell Calcium 2004; 36:61-75. [PMID: 15126057 DOI: 10.1016/j.ceca.2003.11.010] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2003] [Revised: 10/12/2003] [Accepted: 11/12/2003] [Indexed: 10/26/2022]
Abstract
Alterations of neuronal Ca(2+) homeostatic mechanisms could be responsible for many of the cognitive deficits associated with aging in mammals. Mitochondrial participation in Ca(2+) signaling is now recognized as a prominent feature in neuronal physiology. We combined voltage-clamp electrophysiology with Ca(2+)-sensitive ratiometric microfluorimetry and laser scanning confocal microscopy to investigate the participation in Ca(2+) buffering of in situ mitochondria in acutely dissociated basal forebrain neurons from young and aged F344 rats. By pharmacologically blocking mitochondrial Ca(2+) uptake, we determined that mitochondria were not involved in rapid buffering of small Ca(2+) influx through voltage-gated Ca(2+) channels (VGCCs) in the somatic compartment. For larger Ca(2+) influx, aged mitochondria showed a significant buffering deficit. Evidence obtained with the potentiometric indicator, JC-1, suggests a significantly reduced mitochondrial membrane potential in aged neurons. These results support the interpretation that there is a fundamental difference in the way young and aged neurons buffer Ca(2+), and a corresponding difference in the quality of the Ca(2+) signal experienced by young and aged neurons for different intensities of cytoplasmic Ca(2+) influx.
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Affiliation(s)
- David Murchison
- Department of Medical Pharmacology and Toxicology, College of Medicine, Texas A&M University System Health Science Center, College Station, TX 77843-1114, USA
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32
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Abstract
Understanding the cellular mechanisms that characterize the functional changes of the aged brain is an ongoing and formidable challenge for the neuroscience community. Evidence now links changes in Ca(2+) influx and homeostasis with perturbations induced by the aging process in the function of the main intracellular organelles involved in Ca(2+) regulation: the endoplasmic reticulum and mitochondria. New perspectives are also offered by recent gene microarray studies, illustrating the multifactorial nature of the aging process.
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33
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Kumar A, Foster TC. Enhanced long-term potentiation during aging is masked by processes involving intracellular calcium stores. J Neurophysiol 2004; 91:2437-44. [PMID: 14762159 DOI: 10.1152/jn.01148.2003] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The contribution of Ca(2+) release from intracellular Ca(2+) stores (ICS) for regulation of synaptic plasticity thresholds during aging was investigated in hippocampal slices of old (22-24 mo) and young adult (5-8 mo) male Fischer 344 rats. Inhibition of Ca(2+)-induced Ca(2+) release by thapsigargin, cyclopiazonic acid (CPA), or ryanodine during pattern stimulation near the threshold for synaptic modification (5 Hz, 900 pulses) selectively induced long-term potentiation (LTP) to CA1 Schaffer collateral synapses of old rats. Increased synaptic strength was specific to test pathways and blocked by AP-5. Intracellular recordings demonstrated that ICS plays a role in the augmentation of the afterhyperpolarization (AHP) in old rats. The decrease in the AHP by ICS inhibition was reversed by the L-channel agonist, Bay K8644. Under conditions of ICS inhibition and a Bay K8644-mediated enhancement of the AHP, pattern stimulation failed to induce LTP, consistent with the idea that the AHP amplitude shapes the threshold for LTP induction. Finally, ICS inhibition was associated with an increase in the N-methyl-d-aspartate (NMDA) receptor component of synaptic transmission in old animals. This increase in the synaptic response was blocked by the calcineurin inhibitor FK506. The results reveal an age-related increase in susceptibility to LTP-induction that is normally inhibited by ICS and suggest that the age-related shift in Ca(2+) regulation and Ca(2+)-dependent synaptic plasticity is coupled to changes in cell excitability and NMDA receptor function through ICS.
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Affiliation(s)
- Ashok Kumar
- Department of Neuroscience, McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA
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34
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Toescu EC, Verkhratsky A. Neuronal ageing from an intraneuronal perspective: roles of endoplasmic reticulum and mitochondria. Cell Calcium 2003; 34:311-23. [PMID: 12909078 DOI: 10.1016/s0143-4160(03)00142-8] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The nature of brain ageing and the age-dependent decline in cognitive functions remains poorly understood. Physiological brain ageing is characterised by mild mental dysfunctions, whereas age-dependent neurodegeneration, as illustrated by Alzheimer disease (AD), results rapidly in severe dementia. These two states of the aged brain, the physiological and the pathological, are fundamentally different as the latter stems from significant neuronal loss, whereas the former develops without significant neuronal demise. In this paper, we review the changes in neuronal Ca(2+) homeostasis that occur during brain ageing, and conclude that normal, physiological ageing is characterised mainly by a decrease of neuronal homeostatic reserve, defined as the capacity to respond effectively to functional and metabolic stressors, but does not reach the trigger required to induce neuronal death. In contrast, during neurodegenerative states, Ca(2+) homeostasis is affected early during the pathological process and result in significant neuronal demise. We also review recent evidence suggesting that the endoplasmic reticulum (ER) might play an important role in controlling the balance between healthy and pathological neuronal ageing.
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Affiliation(s)
- Emil C Toescu
- Department of Physiology, The University of Birmingham, B15 2TT Edgbaston, UK.
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35
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Foster TC. Regulation of synaptic plasticity in memory and memory decline with aging. PROGRESS IN BRAIN RESEARCH 2002; 138:283-303. [PMID: 12432775 DOI: 10.1016/s0079-6123(02)38083-x] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Thomas C Foster
- Department of Molecular and Biomedical Pharmacology, University of Kentucky, College of Medicine, Lexington, KY 40536, USA.
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36
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Clodfelter GV, Porter NM, Landfield PW, Thibault O. Sustained Ca2+-induced Ca2+-release underlies the post-glutamate lethal Ca2+ plateau in older cultured hippocampal neurons. Eur J Pharmacol 2002; 447:189-200. [PMID: 12151011 DOI: 10.1016/s0014-2999(02)01843-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Several studies have shown that a prolonged Ca(2+) elevation follows a glutamate-mediated excitotoxic insult in cultured neurons, and may be associated with impending cell death. Recently, we showed that the prolonged Ca(2+) elevation that emerges as neurons age in culture is specifically linked to an age-related increase in excitotoxic vulnerability. However, the multiple sources of Ca(2+) that contribute to Ca(2+) elevation during and after glutamate exposure are not well understood. Here, we examined the Ca(2+) sources of the age-related prolonged Ca(2+) elevation in cultured hippocampal neurons. Studies with caffeine showed that the ryanodine receptor-dependent releasable pool of Ca(2+) from intracellular stores was similar in older and younger neurons. Thapsigargin, which inhibits intracellular store refilling, did not mimic the age-related prolonged Ca(2+) elevation and, in fact, partially reduced it. Ryanodine, which blocks Ca(2+)-induced Ca(2+)-release (CICR) from stores, completely blocked the age-related prolonged Ca(2+) elevation following glutamate exposure but did not alter maximal Ca(2+) elevation during the glutamate exposure. Thus, we conclude that sustained CICR plays a selective and key role in generating the lethal, age-related, prolonged Ca(2+) elevation, and is the likely mechanism underlying age-related, enhanced vulnerability to excitotoxicity in neurons.
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Affiliation(s)
- Gregory V Clodfelter
- University of Kentucky Medical Center, Department of Molecular and Biomedical Pharmacology, MS-320, 800 Rose Street, Lexington, KY 40536, USA
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37
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Abstract
The aging process at the cellular, organ and whole organism levels is in many respects a mystery. A common bias among those who study aging is that cellular homeostasis "generally falls apart". The assumption of a general deterioration in cellular homeostasis does not take into account that many individuals age quite well maintaining even robust physiological and mental functions. One facet of aging studies that has come to the forefront is the impact of age on the control of the ion messenger, calcium. Emerging evidence suggests that despite age-related declines in any one component or multiple components of the calcium buffering systems, compensatory mechanisms may be able to maintain overall calcium homeostasis. This brief review focuses specifically on the ability of peripheral neurons to maintain control of the ion messenger calcium with advancing age. In addition, the idea that the impact of age on calcium homeostasis may be more subtle due to complex and integrated mechanisms that control this ion is discussed.
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Affiliation(s)
- William J Pottorf
- Department of Pharmacology, School of Medicine, Loma Linda University, CA 92350, USA
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38
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Han SH, McCool BA, Murchison D, Nahm SS, Parrish AR, Griffith WH. Single-cell RT-PCR detects shifts in mRNA expression profiles of basal forebrain neurons during aging. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 2002; 98:67-80. [PMID: 11834297 DOI: 10.1016/s0169-328x(01)00322-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The medial septum and nucleus of the diagonal band (MS/nDB) contain cholinergic and GABAergic neuronal populations that have been identified based on immunohistochemical staining and/or electrophysiological properties. We explored the molecular diversity of MS/nDB neurons using single-cell reverse transcription-polymerase chain reaction (scRT-PCR) to assess gene expression profiles during aging in individual neurons acutely isolated from young (2-4 months) and aged (26-27 months) F344 rats. Neuronal gene expression profiles were characterized by detection of mRNAs for choline acetyltransferase (ChAT, cholinergic) and glutamate decarboxylase (GAD67, GABAergic), as well as mRNAs for calcium binding proteins (CaBPs) calbindin-D28k, calretinin and parvalbumin. Four major neuronal populations were identified: ChAT-positive (ChAT+) cells, GAD-positive (GAD+) cells, ChAT+/GAD+ cells and ChAT negative/GAD negative (ChAT-/GAD-) cells. With age, the percentage of cells expressing ChAT mRNA decreased from 53% in young to 40%, and the expression of GAD67 mRNA was reduced from 56 to 35% of the cells tested. The percentage of cells with detectable levels of both ChAT and GAD67 mRNA was reduced from 24% in young to 9% in aged. Concomitantly, the percentage of ChAT-/GAD- cells increased from 15 to 34% with age. Of the CaBPs, calretinin expression was observed most frequently in this study, and its detection decreased from 33 to 22% of the cells with age. Observations concerning the CaBPs were confirmed using in situ hybridization. These results suggest a shift in the mRNA expression profiles of MS/nDB neuronal populations during aging and exemplify the molecular diversity of cholinergic and GABAergic cells.
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Affiliation(s)
- Sun-Ho Han
- Department of Medical Pharmacology and Toxicology, College of Medicine, Texas A&M University System Health Science Center, College Station, TX 77843-1114, USA
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39
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Elevated postsynaptic [Ca2+]i and L-type calcium channel activity in aged hippocampal neurons: relationship to impaired synaptic plasticity. J Neurosci 2002. [PMID: 11739583 DOI: 10.1523/jneurosci.21-24-09744.2001] [Citation(s) in RCA: 200] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Considerable evidence supports a Ca(2+) dysregulation hypothesis of brain aging and Alzheimer's disease. However, it is still not known whether (1) intracellular [Ca(2+)](i) is altered in aged brain neurons during synaptically activated neuronal activity; (2) altered [Ca(2+)](i) is directly correlated with impaired neuronal plasticity; or (3) the previously observed age-related increase in L-type voltage-sensitive Ca(2+) channel (L-VSCC) density in hippocampal neurons is sufficient to impair synaptic plasticity. Here, we used confocal microscopy to image [Ca(2+)](i) in single CA1 neurons in hippocampal slices of young-adult and aged rats during repetitive synaptic activation. Simultaneously, we recorded intracellular EPSP frequency facilitation (FF), a form of short-term synaptic plasticity that is impaired with aging and inversely correlated with cognitive function. Resting [Ca(2+)](i) did not differ clearly with age. Greater elevation of somatic [Ca(2+)](i) and greater depression of FF developed in aged neurons during 20 sec trains of 7 Hz synaptic activation, but only if the activation triggered repetitive action potentials for several seconds. Elevated [Ca(2+)](i) and FF also were negatively correlated in individual aged neurons. In addition, the selective L-VSCC agonist Bay K8644 increased the afterhyperpolarization and mimicked the depressive effects of aging on FF in young-adult neurons. Thus, during physiologically relevant firing patterns in aging neurons, postsynaptic Ca(2+) elevation is closely associated with altered neuronal plasticity. Moreover, selectively increasing postsynaptic L-VSCC activity, as occurs in aging, negatively regulated a form of short-term plasticity that enhances synaptic throughput. Together, the results elucidate novel processes that may contribute to impaired cognitive function in aging.
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40
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Pottorf WJ, De Leon DD, Hessinger DA, Buchholz JN. Function of SERCA mediated calcium uptake and expression of SERCA3 in cerebral cortex from young and old rats. Brain Res 2001; 914:57-65. [PMID: 11578597 DOI: 10.1016/s0006-8993(01)02773-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Previous work on peripheral sympathetic neurons indicated that a decline in sarco/endoplasmic reticulum calcium ATPase (SERCA) function occurs with advancing age. Therefore, an age-related decline in mechanisms controlling intracellular calcium homeostasis could contribute to altered neuronal function and/or degeneration. In this study we sought to extend the findings on peripheral neurons and to detect possible age-related declines in SERCA function and expression of SERCA3 in central neurons from cerebral cortex from young (6-month) and old (20-month) rats. Functional studies compared ATP-dependent 45Ca(2+)-uptake into microsomes and plasma membrane vesicles (PMVs). We and found no significant difference in 45Ca(2+)-uptake between microsomes or PMVs between young and old animals. On the other hand expression of SERCA3 mRNA in rat cerebral cortex showed a significant decline with advancing age. However, comparison of SERCA3 protein content did not reveal a corresponding decline; implying that SERCA mRNA turnover rates may be greater in the younger group. Although the present work with rat cerebral cortex does not indicate an age-related decline in SERCA function, previous work from our laboratory on sympathetic nerves and by others on the hippocampus indicate such a decline. In light of our previous and current studies, aging may affect calcium homeostatic mechanisms in central and peripheral autonomic neurons differently.
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Affiliation(s)
- W J Pottorf
- Department of Pharmacology, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA
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41
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Abstract
Brain aging, Alzheimer disease and stroke share common elements of deficits in calcium regulation, declines in mitochondrial function, increases in generation of reactive oxygen species (ROS), accumulated damage from ROS and immune system dysfunction. The problem is to distinguish less significant side reactions, such as gray hair, from aspects of aging that contribute to disease. Toward establishing cause and effect relationships, a neuron cell culture system is described that allows comparisons with age under uniform environmental conditions. This neuron culture model indicates that susceptibility to death by apoptosis and consequences of the inflammatory response from beta-amyloid are age-related and an inherent characteristic of the neurons. Further mechanistic investigations are possible. New therapeutic approaches are suggested that combine inhibition of calcium overloads (calcium channel blockers), reduced ROS damage (melatonin, N-acetyl-cysteine), and bolstered mitochondrial function and energy generation (creatine). Together with newly demonstrated capabilities for adult and aged neuron regeneration and multiplication, i.e. plasticity, these approaches offer new hope toward reversing age-related decrements and damage from neurodegenerative disease.
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Affiliation(s)
- G J Brewer
- Department of Neurology, School of Medicine, Southern Illinois University, Springfield, IL, 62794-9626, USA.
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42
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Scanlon JM, Brocard JB, Stout AK, Reynolds IJ. Pharmacological investigation of mitochondrial ca(2+) transport in central neurons: studies with CGP-37157, an inhibitor of the mitochondrial Na(+)-Ca(2+) exchanger. Cell Calcium 2000; 28:317-27. [PMID: 11115371 DOI: 10.1054/ceca.2000.0171] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Mitochondria buffer large changes in [Ca(2+)](i)following an excitotoxic glutamate stimulus. Mitochondrial sequestration of [Ca(2+)](i)can beneficially stimulate oxidative metabolism and ATP production. However, Ca(2+)overload may have deleterious effects on mitochondrial function and cell survival, particularly Ca(2+)-dependent production of reactive oxygen species (ROS) by the mitochondria. We recently demonstrated that the mitochondrial Na(+)-Ca(2+)exchanger in neurons is selectively inhibited by CGP-37157, a benzothiazepine analogue of diltiazem. In the present series of experiments we investigated the effects of CGP-37157 on mitochondrial functions regulated by Ca(2+). Our data showed that 25 microM CGP-37157 quenches DCF fluorescence similar to 100 microM glutamate and this effect was enhanced when the two stimuli were applied together. CGP-37157 did not increase ROS generation and did not alter glutamate or 3mM hydrogen-peroxide-induced increases in ROS as measured by DHE fluorescence. CGP-37157 induces a slight decrease in intracellular pH, much less than that of glutamate. In addition, CGP-37157 does not enhance intracellular acidification induced by glutamate. Although it is possible that CGP-37157 can enhance mitochondrial respiration both by blocking Ca(2+)cycling and by elevating intramitochondrial Ca(2+), we did not observe any changes in ATP levels or toxicity either in the presence or absence of glutamate. Finally, mitochondrial Ca(2+)uptake during an excitotoxic glutamate stimulus was only slightly enhanced by inhibition of mitochondrial Ca(2+)efflux. Thus, although CGP-37157 alters mitochondrial Ca(2+)efflux in neurons, the inhibition of Na(+)-Ca(2+)exchange does not profoundly alter glutamate-mediated changes in mitochondrial function or mitochondrial Ca(2+)content.
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Affiliation(s)
- J M Scanlon
- Department of Pharmacology, University of Pittsburgh, School of Medicine, Pittsburgh, USA
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43
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Griffith WH, Jasek MC, Bain SH, Murchison D. Modification of ion channels and calcium homeostasis of basal forebrain neurons during aging. Behav Brain Res 2000; 115:219-33. [PMID: 11000422 DOI: 10.1016/s0166-4328(00)00260-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this paper we review the last several years of work from our lab with attention to changes in the properties of basal forebrain neurons during aging. These neurons play a central role in behavioral functions, such as: attention, arousal, cognition and autonomic activity, and these functions can be adversely affected during aging. Therefore, it is fundamental to define the cellular mechanisms of aging in order to understand the basal forebrain and to correct deficits associated with aging. We have examined changes in the physiological properties of basal forebrain neurons during aging with whole-cell and single-channel patch-clamp, as well as, microfluorimetric measurements of intracellular calcium concentrations. These studies contribute to the understanding of integration within the basal forebrain and to the identification of age-related changes within central mammalian neurons. Although extensive functional/behavioral decline is often assumed to occur during aging, our data support an interpretation of compensatory increases in function for excitatory amino acid receptors, GABA(A) receptors, voltage-gated calcium currents and calcium homeostatic mechanisms. We believe that these changes occur to compensate for decrements accruing with age, such as decreased synaptic contacts, ion imbalances or neuronal loss. The basal forebrain must retain functionality into late aging if senescence is to be productive. Thus, it is critical to recognize the potential cellular and subcellular targets for therapeutic interventions intended to correct age-related behavioral deficits.
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Affiliation(s)
- W H Griffith
- Department of Medical Pharmacology and Toxicology, College of Medicine, Texas A&M University System Health Science Center, College Station, TX 77843-1114, USA.
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44
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Pottorf WJ, Duckles SP, Buchholz JN. SERCA function declines with age in adrenergic nerves from the superior cervical ganglion. ACTA ACUST UNITED AC 2000; 20:281-90. [PMID: 11350493 DOI: 10.1046/j.1365-2680.2000.00194.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
1. Intracellular calcium is a universal second messenger integrating numerous cellular pathways. An age-related breakdown in the mechanisms controlling [Ca2+]i homeostasis could contribute to neuronal degeneration. One component of neuronal calcium regulation believed to decline with age is the function of sarco/endoplasmic reticulum calcium ATPase (SERCA) pumps. 2. Therefore we investigated the impact of age on the capacity of SERCA pumps to control high (68 mM) [K+]-evoked [Ca2+]i-transients in acutely dissociated superior cervical ganglion (SCG) cells from 6- and 20-month-old Fisher-344 rats. Calcium transients were measured by fura-2 microfluorometry in the presence of vanadate (0.1 microM) to selectively block plasma membrane calcium ATPase (PMCA) pumps, dinitrophenol (100 microM) to block mitochondrial calcium uptake and extracellular sodium replaced with tetraethylammonium to block Na+/Ca2+-exchanger, thus forcing the neuronal cells to rely on SERCA uptake to control [Ca2+]i homeostasis. 3. In the presence of these calcium buffering blockers, the rate of recovery of [Ca2+]i was significantly slower and time to recover to approximately 90% of resting [Ca2+]i was significantly greater in SCG cells from old (20 months) compared with young (6 months) animals. 4. This age-related change in the recovery phase of [K+]-evoked [Ca2+]i-transients could not be explained by differences in the sensitivity of SCG cells to the calcium buffering blockers, as no age-related difference in basal [Ca2+]i was observed. 5. These studies illustrate that when rat SCG cells are forced to rely on SERCAs to buffer [K+]-evoked [Ca2+]i-transients, an age-related decline in SERCA function is revealed. Such age-related declines in calcium regulation coupled with neuronal sensitivity to calcium overload underscore the importance of understanding the components of [Ca2+]i homeostasis and the functional compensation that may occur with advancing age.
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Affiliation(s)
- W J Pottorf
- Department of Pharmacology, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA
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45
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Dove LS, Nahm SS, Murchison D, Abbott LC, Griffith WH. Altered calcium homeostasis in cerebellar Purkinje cells of leaner mutant mice. J Neurophysiol 2000; 84:513-24. [PMID: 10899223 DOI: 10.1152/jn.2000.84.1.513] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The leaner (tg(la)) mouse mutation occurs in the gene encoding the voltage-activated Ca(2+) channel alpha(1A) subunit, the pore-forming subunit of P/Q-type Ca(2+) channels. This mutation results in dramatic reductions in P-type Ca(2+) channel function in cerebellar Purkinje neurons of tg(la)/tg(la) mice that could affect intracellular Ca(2+) signaling. We combined whole cell patch-clamp electrophysiology with fura-2 microfluorimetry to examine aspects of Ca(2+) homeostasis in acutely dissociated tg(la)/tg(la) Purkinje cells. There was no difference between resting somatic Ca(2+) concentrations in tg(la)/tg(la) cells and in wild-type (+/+) cells. However, by quantifying the relationship between intracellular Ca(2+) elevations and depolarization-induced Ca(2+) influx, we detected marked alterations in rapid calcium buffering between the two genotypes. Calcium buffering values (ratio of bound/free ions) were significantly reduced in tg(la)/tg(la) (584 +/- 52) Purkinje cells relative to +/+ (1,221 +/- 80) cells. By blocking the endoplasmic reticulum (ER) Ca(2+)-ATPases with thapsigargin, we observed that the ER had a profound impact on rapid Ca(2+) buffering that was also differential between tg(la)/tg(la) and +/+ Purkinje cells. Diminished Ca(2+) uptake by the ER apparently contributes to the reduced buffering ability of mutant cells. This report constitutes one of the few instances in which the ER has been implicated in rapid Ca(2+) buffering. Concomitant with this reduced buffering, in situ hybridization with calbindin D28k and parvalbumin antisense oligonucleotides revealed significant reductions in mRNA levels for these Ca(2+)-binding proteins (CaBPs) in tg(la)/tg(la) Purkinje cells. All of these results suggest that alterations of Ca(2+) homeostasis in tg(la)/tg(la) mouse Purkinje cells may serve as a mechanism whereby reduced P-type Ca(2+) channel function contributes to the mutant phenotype.
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Affiliation(s)
- L S Dove
- Department of Medical Pharmacology and Toxicology, College of Medicine, Texas A&M University System Health Science Center, College Station 77843-1114, Texas, USA
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46
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Pottorf WJ, Duckles SP, Buchholz JN. Mechanisms of calcium buffering in adrenergic neurones and effects of ageing: testing the limits of homeostasis. JOURNAL OF AUTONOMIC PHARMACOLOGY 2000; 20:63-75. [PMID: 11095545 DOI: 10.1046/j.1365-2680.2000.00165.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- W J Pottorf
- Department of Pharmacology, Loma Linda University School of Medicine, CA 92350, USA
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47
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Murchison D, Griffith WH. Mitochondria buffer non-toxic calcium loads and release calcium through the mitochondrial permeability transition pore and sodium/calcium exchanger in rat basal forebrain neurons. Brain Res 2000; 854:139-51. [PMID: 10784115 DOI: 10.1016/s0006-8993(99)02297-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Mitochondria participate in intracellular Ca2+ buffering and signalling. They are also major mediators of cell death. Toxic Ca2+ accumulation in mitochondria is widely believed to initiate cell death in many cell types by opening the permeability transition pore (PTP). In non-neuronal cells, the PTP has been implicated as a Ca2+ release mechanism in physiological Ca2+ signalling. In neurons, Ca2+ release from mitochondria has been attributed primarily to mitochondrial Na+/Ca2+ exchange. Using fura-2 ratiometric microfluorimetry in acutely dissociated rat basal forebrain neurons, we show that mitochondria are able to buffer non-toxic Ca2+ loads arising from caffeine-sensitive internal stores or from extracellular influx through voltage gated channels. We also show that these non-toxic Ca2+ loads are reversibly released from mitochondria through the PTP and the Na+/Ca2+ exchanger. Evoked Ca2+ transients have characteristic peak and shoulder features mediated by mitochondrial buffering and release. Depolarizing mitochondria with carbonyl cyanide m-chlorophenylhydrazone (CCCP, 5 microM) causes release of mitochondrial Ca2+ and prevents Ca2+ uptake. In CCCP, the magnitudes of evoked Ca2+ transients are increased, and the peak and shoulder features are eliminated. The PTP antagonist, cyclosporin A, (CSA, 2 microM) and the Na+/Ca2+ exchange blocker, clonazepam, (CLO, 20 microM) reversibly inhibited both the shoulder features of evoked Ca2+ transients and Ca2+ transients associated with CCCP application. We suggest that central neuronal mitochondria buffer and release Ca2+ through the PTP and Na+/Ca2+ exchanger during physiological Ca2+ signalling. We also suggest that CLO blocks both the PTP and the mitochondrial Na+/Ca2+ exchanger.
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Affiliation(s)
- D Murchison
- Department of Medical Pharmacology and Toxicology, College of Medicine, Texas A&M University System Health Science Center, College Station 77843-1114, USA
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